topic Re: How can I get I3C 12.5M clock? in MCX Microcontrollers

How can I get I3C 12.5M clock?

yvan_yan — Fri, 30 May 2025 02:54:11 GMT

Chip is MCXN947, from the spec, it says I3C two-wire multidrop bus that is capable of 12.5 MHz clock speeds with up to 11 devices.

In fact, I cannot get 12.5M clock, How can I config if we want run up to 12.5MHz baudrate?

Thanks.

Harry_Zhang — Fri, 30 May 2025 08:36:13 GMT

You can refer to the frdmmcxn947_i3c_polling_b2b_transfer_master examples in the SDK.

Harry

yvan_yan — Fri, 30 May 2025 09:13:03 GMT

Thanks for your reply.

Have you check the clock, EXAMPLE_I3C_PP_BAUDRATE is 1.25MHz by default. If I set to 12.5MHz, the clock isn't correct.

Yvan

yvan_yan — Wed, 04 Jun 2025 02:02:39 GMT

Could you help me check this problem?

We can get I3C 10MHz clock, but we cannot get higher

Harry_Zhang — Wed, 04 Jun 2025 09:26:51 GMT

I will check it and reply to you.

Harry

yvan_yan — Thu, 05 Jun 2025 02:19:45 GMT

Thanks a lot. Looking forward to your reply.

yvan_yan — Wed, 11 Jun 2025 06:37:56 GMT

We can run I3C sdr mode in 12.5MHz.

But i3c hdr-ddr mode cannot run above 3MHz, Is i3c ddr mode capable of operating in 12.5MHz?

Yvan

Harry_Zhang — Wed, 11 Jun 2025 10:25:19 GMT

Yes,

According to the MCXNx4x data sheet.

Both SDR and DDR can run at 12.5M.

Harry